Fujitsu MB91401 Notes as device Treatment of Unused Input Pins, About Mode pins MDI2 to MDI0

Prelminary	MB91401
2004.11.12

•Notes as device

Treatment of Unused Input Pins

It causes the malfunction that the unused input terminal is made open, and do the processing such as 1 stack or 0 stacks.

About Mode pins (MDI2 to MDI0)

Connect these pins with the input buffer by 1 to 1 to prevent the malfunction by the noise, and connect directly to VDD or VSS outside of ASIC.

Operation at start-up

Specify set initialization reset (INIT) with the terminal INITXI when you turn on the power supply.

Moreover, connect "L" level input to the terminal INITXI until the input clock is steady.

About watch dog timer

The watchdog timer function of this macro monitors a program to check whether it delays a reset within a certain period of time. If the program runs out of control and fails to delay the reset, the watchdog timer function resets the CPU.

Therefore, it keeps operating until reset is specified when the watchdog timer function is made effective once.

Exceptionally, the reset postponement is automatically done under the condition that the program execution of CPU stops. Refer to the paragraph of the function explanation of the watchdog timer for the condition of applying to this exception.

There is a possibility that watchdog reset is not generated when entering the above-mentioned state by the reckless driving of the system. In that case, please specify reset (INIT) from external INITX terminal.

Restrictions

•Clock control block

•Secure the clock stability waiting time at "L" input to INITXI.

•When entering the standby mode, use the following sequences after using the synchronous standby mode

(TBCR:set at the bit8 SYNCS bit of timebase counter control register).

(LDI	#value_of_standby, R0)	; Value_of standby is write data to STCR.
(LDI	#_STCR, R12)	; _STCR is address (481H) of STCR.
STB	R0, @R12	; Write to standby control register (STCR).
LDUB	@R12, R0	; STCR read for synchronous standby
LDUB	@R12, R0	; Dummy re-read of STCR
NOP
NOP

NOP

NOP

NOP

In addition, set the I-flag and the ILM and ICR registers to branch to an interrupt handler when the interrupt handler triggers the microcontroller to return from the standby mode.

•Please do not do the following when the monitor debugger is used.

•Please do not set the break point to the above-mentioned instruction row.

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